docs: installation: upgrade-notes: add breaking changes for v2.0 through v4.2

[eschabell]

• v2.0: mbedTLS removed as TLS backend; OpenSSL now required for source builds
• v3.0: HTTP/2 enabled by default for opentelemetry, splunk, elasticsearch,
  and http input plugins; add http2 off if clients or proxies lack HTTP/2 support
• v4.0: official packages dropped for Ubuntu 16.04, 18.04, and 20.04
• v4.0: Kafka plugins disabled in official packages for CentOS 7 and
  Amazon Linux 2 (ARM64) due to librdkafka glibc requirements
• v4.2: Vivo exporter HTTP endpoint paths changed to /api/v1/ prefix

Fixes #2393

Summary by CodeRabbit

• Documentation
  • Added v4.2 upgrade notes: Vivo exporter HTTP endpoints now use a standardized /api/v1/ prefix for logs, metrics, traces, and internal metrics; includes a concise endpoint table and guidance to update tooling.
  • Retained and preserved existing upgrade documentation for earlier versions.

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📥 Commits

Reviewing files that changed from the base of the PR and between d72b263 and 124cbd5.

📒 Files selected for processing (1)

• installation/upgrade-notes.md

📝 Walkthrough

Walkthrough

Adds a v4.2 upgrade note to installation/upgrade-notes.md documenting that all Vivo exporter HTTP endpoints (logs, metrics, traces, internal metrics) now require the /api/v1/ prefix; retains prior upgrade-note sections for v4.0, v3.0, v2.0, and v1.9.9.

Changes

Cohort / File(s)	Summary
Upgrade Notes Documentation installation/upgrade-notes.md	Added v4.2 upgrade note documenting Vivo exporter HTTP endpoints moving to the /api/v1/ prefix (logs, metrics, traces, internal metrics), updated endpoint table and examples; existing v4.0, v3.0, v2.0, v1.9.9 sections left intact.

Estimated code review effort

🎯 1 (Trivial) | ⏱️ ~3 minutes

Possibly related PRs

• Updated for new api endpoints and missing config options for vivo exporter output plugin docs. Fixes #2217. #2224 — Documents the same Vivo exporter API migration to /api/v1/ endpoints and updates examples.

Suggested reviewers

• cosmo0920
• patrick-stephens

Poem

🐰 I hopped through docs to mark the way,
Vivo endpoints now in /api/v1/ play,
Logs, metrics, traces neatly aligned,
Upgrade notes penned, tidy and kind —
A tiny rabbit's celebratory sway. 🥕

🚥 Pre-merge checks | ✅ 5

✅ Passed checks (5 passed)

Check name	Status	Explanation
Description Check	✅ Passed	Check skipped - CodeRabbit’s high-level summary is enabled.
Title check	✅ Passed	The title accurately describes the main change: adding breaking change notes for multiple Fluent Bit versions (v2.0-v4.2) to the upgrade-notes documentation.
Linked Issues check	✅ Passed	The PR directly addresses issue #2393 by updating the upgrade-notes documentation with breaking changes for versions v2.0 through v4.2, meeting the stated objective.
Out of Scope Changes check	✅ Passed	All changes are scoped to the upgrade-notes documentation file, directly supporting the objective to update breaking change notes for versions v2.0 through v4.2.
Docstring Coverage	✅ Passed	No functions found in the changed files to evaluate docstring coverage. Skipping docstring coverage check.

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[coderabbitai]

Actionable comments posted: 2

🤖 Prompt for all review comments with AI agents

Verify each finding against the current code and only fix it if needed.

Inline comments:
In `@installation/upgrade-notes.md`:
- Line 55: Update the sentence that currently reads "If your clients do not
support HTTP/2, or if you have a reverse proxy or load balancer that does not
handle HTTP/2 correctly, add `http2 off` to the affected input plugin
configuration section." to use contractions per repo style: change "do not" to
"don't" and "does not" to "doesn't" while keeping the rest of the text and the
`http2 off` code span unchanged.
- Line 32: Add the missing exception "Xenial" to the spelling exceptions list by
editing Spelling-exceptions.txt (under the FluentBit style) and insert the word
Xenial in alphabetical order with the other entries so the recurring spelling
warning for Ubuntu 16.04 is suppressed; ensure the entry matches casing exactly
("Xenial") and save the file.

---

ℹ️ Review info

Configuration used: defaults

Review profile: CHILL

Plan: Pro

📥 Commits

Reviewing files that changed from the base of the PR and between dc38f3c and 943773f.

📒 Files selected for processing (1)

• installation/upgrade-notes.md

[eschabell]

@cosmo0920 and @patrick-stephens ready for review!